U.S. patent application number 16/337850 was filed with the patent office on 2020-01-30 for biosignal headphones.
The applicant listed for this patent is MINDSET INNOVATION INC.. Invention is credited to David DOYON, Christopher FAUST, Jacob FLOOD, Warren ROBINSON, Xin YAO.
Application Number | 20200029881 16/337850 |
Document ID | / |
Family ID | 61762466 |
Filed Date | 2020-01-30 |
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United States Patent
Application |
20200029881 |
Kind Code |
A1 |
FLOOD; Jacob ; et
al. |
January 30, 2020 |
BIOSIGNAL HEADPHONES
Abstract
There are described headphones comprising earcups to be placed
about ears of a user, with a headband linking the earcups and to be
extending above a head of the user. A flexible band distinct from
the headband is secured below the headband for contact with the
head of the user. Removable headband sensors are embedded in the
flexible band and have a portion thereof protruding downwardly from
the flexible band to reach the scalp. The flexible band has a
flexibility which makes the flexible band deform under the weight
of the earcups to conform with the head of the user to ensure high
quality contact between the headband electrodes and the scalp.
There are further provided earcup electrodes on the earcups for
contact with a region on or behind an ear of the user. Signals from
the electrodes can be used for different purposes such as
concentration monitoring and feedback.
Inventors: |
FLOOD; Jacob; (Brossard,
CA) ; DOYON; David; (Saint-Constant, CA) ;
ROBINSON; Warren; (Toronto, CA) ; YAO; Xin;
(Brossard, CA) ; FAUST; Christopher;
(Saint-Laurent, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MINDSET INNOVATION INC. |
Brossard |
|
CA |
|
|
Family ID: |
61762466 |
Appl. No.: |
16/337850 |
Filed: |
September 29, 2017 |
PCT Filed: |
September 29, 2017 |
PCT NO: |
PCT/CA2017/051162 |
371 Date: |
March 28, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62401263 |
Sep 29, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04R 1/1008 20130101;
H04R 1/105 20130101; H04R 1/1041 20130101; A61B 5/0478 20130101;
A61B 5/168 20130101; H04R 1/1083 20130101; H04R 2410/05 20130101;
A61B 5/0482 20130101; A61B 5/7264 20130101; H04R 5/0335 20130101;
H04R 2201/10 20130101; A61B 5/6803 20130101; H04R 1/1058
20130101 |
International
Class: |
A61B 5/16 20060101
A61B005/16; H04R 1/10 20060101 H04R001/10; A61B 5/0478 20060101
A61B005/0478; A61B 5/00 20060101 A61B005/00; A61B 5/0482 20060101
A61B005/0482 |
Claims
1. Headphones comprising: earcups to be placed about ears of a
user; a headband linking the earcups and extending above a head of
the user; a flexible band distinct from the headband such as to
flex independently therefrom and secured below the headband for
contact with the head of the user; headband electrode sockets
formed within the flexible band for receiving headband electrodes,
the sockets having an electrically conductive base.
2. The headphones of claim 1, wherein the flexible band has a shape
at rest not conforming with a head by providing the flexible band
with a radius of curvature larger than a radius of curvature of a
top area of a human head.
3. The headphones of claim 2, wherein the flexible band has a
flexibility which makes the flexible band deform under a weight of
the earcups to conform with the head of the user.
4. The headphones of claim 1, wherein the flexible band has a shape
at rest characterized by a radius of curvature between 85 mm and
100 mm, and is made of a resilient material which under the weight
of the headphones, which is between 100 g and 1 kg, adopts a radius
of curvature between 70 mm and 85 mm.
5. The headphones of claim 3, wherein the flexible band is
deformable under the weight of the earcups to conform with the head
of the user, while the headband does not substantially flex.
6. The headphones of claim 1, further comprising headband
electrodes to be embedded in the sockets of the flexible band and
having a portion thereof protruding downwardly from the flexible
band.
7. The headphones of claim 6, wherein the headband electrodes
comprise a flexible substrate and a plurality of legs extending
therefrom and protruding from the flexible band.
8. (canceled)
9. The headphones of claim 8, wherein the flexible substrate is
both electrically conductive and flexible such as to allow the legs
to change orientation with respect to the flexible substrate.
10. The headphones of claim 7, wherein each of the headband
electrodes comprises a male connector to fit with a corresponding
female connector within the base of a corresponding one of the
sockets to hold the headband electrodes in the sockets and form an
electrical connection between the legs and the electrically
conductive base within the sockets.
11. The headphones of claim 6, wherein the headband electrodes are
user-detachable from the base without having to dismount the
flexible band.
12. (canceled)
13. (canceled)
14. (canceled)
15. (canceled)
16. (canceled)
17. (canceled)
18. (canceled)
19. (canceled)
20. (canceled)
21. (canceled)
22. (canceled)
23. (canceled)
24. (canceled)
25. (canceled)
26. (canceled)
27. Headphones comprising: earcups to be placed about ears of a
user; a headband linking the earcups and extending above a head of
the user; a flexible band distinct from the headband and secured
below the headband for contact with the head of the user; headband
electrodes embedded in the flexible band; earcup electrodes on the
earcups for contact with a rear surface of an ear of the user.
28. The headphones of claim 27, wherein the earcup electrodes
comprise conductive fabric.
29. The headphones of claim 28, wherein the earcup electrodes for
contact with the rear surface of the ear are on an inward surface
of the earcup directed toward the rear surface of the ear.
30. The headphones of claim 29, wherein the earcup electrodes for
contact with the rear surface of the ear comprise an upper rear
earcup electrode and a lower rear earcup electrode, respectively
located at an upper rear location and a lower rear location on the
inward surface of the at least one earcup.
31. The headphones of claim 29, further comprising an outward
earcup electrode provided on an outward surface of the earcup
directed toward the head, in a region of the mastoid when the
headphones are worn.
32. A method for collecting EEG data, the method comprising: laying
onto a head of the user a headband of headphones, the headband
linking earcups; contacting with the head of the user a flexible
band distinct from the headband and secured below the headband;
letting the flexible band adopt a shape of a portion of the head of
the user under the weight of the earcups; contacting headband
electrodes embedded in the flexible band with a scalp of the user;
and collecting data from the headband electrodes.
33. The method of claim 32, further comprising collecting data from
the earcup electrodes located on a surface of the earcups.
34. The method of claim 32, further comprising identifying features
in the collected data within time windows of the collected data and
upon identifying the features, feeding the features to a machine
learning classifier to identify patterns in the features.
35. (canceled)
36. The method of claim 35, wherein pattern identification
comprises determining a state of concentration, and upon
identification of the patterns, feeding the patterns to a
meta-classifier to personalize pattern identification.
37. (canceled)
38. The method of claim 36, further comprising upon determining a
state of concentration, providing a feedback to the user, the
feedback being dependent on the state of concentration as
determined and wherein providing the feedback comprises determining
a moment when to provide the feedback that is expected to maximize
an effect of the feedback to the user.
39. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit or priority from provisional
U.S. patent application 62/401,263, filed Sep. 29, 2016, the
specification of which is hereby incorporated herein by reference
in its entirety.
BACKGROUND
(a) Field
[0002] The subject matter disclosed generally relates to
consumer-grade biosensors. More specifically, it relates to
headphones with EEG sensors and a method for operating them.
(b) Related Prior Art
[0003] Electroencephalography (EEG) has been used in clinical
settings in the last decades as a tool to measure brain activity.
Multi-thousand-dollar, clinical-grade EEG machines use electrodes
to measure voltages on the scalp, in order to infer which regions
of the brain are active. Recently, more sophisticated techniques
have been used to detect precise brain activity, such as responses
to stimulus, and anxiety. The principle of neurofeedback presents
the output of EEG brain scans as a feedback to users in order to
treat a number of neurological disorders, such as depression or
attention deficit disorder.
[0004] The prior art technologies are limited to laboratory
settings using a 21-sensor cap, conductive paste (applied below wet
electrodes), and multi-thousand-dollar clinical-grade amplifiers.
Neurofeedback can be given under controlled conditions, while
supervised by a trained clinician.
[0005] Clinical-grade EEG devices are 21-electrode caps, connected
to standalone data acquisition consoles. Interpretation of the
resulting signals requires the help of a trained clinician.
[0006] Over the last decades, EEG technology has mostly been
limited to clinical use. Neurofeedback protocols are administered
under the supervision of a trained clinician, for the purpose of
treating a variety of medical conditions, including but not limited
to anxiety disorder and attention deficit disorder. Several recent
technological changes have permit the above invention to become
realizable.
[0007] In addition to clinical-grade devices, the prior art
technology is available as consumer-grade products. Indeed, there
have been attempts to transform the case-limited clinical-grade
technology into a portable device, such as a headband.
[0008] The consumer-grade EEG devices are portable, standalone
bands that attach to the head of the user. These devices use
internal computation to automate the role of the clinician in the
neurofeedback process. Examples can be found in WO2016070188A1,
WO2016079525A1, US20170027467A1, US20100280338A1, U.S. Pat. Nos.
8,731,633, 8,781,570, or 5,740,812.
[0009] These devices suffer from various drawbacks. Notably, they
require users to sit down for a deliberate neurofeedback session,
which requires the full attention of the user. Moreover, they do
not provide reliable quality in data collection, and are not suited
for data collection in various contexts as they are very sensitive
to perturbations.
SUMMARY
[0010] Firstly, innovations in high-input-impedance amplifiers and
high-resolution analog to digital converters has allowed for the
reduced cost and size of these electronic components. This change
has permit us to construct a portable EEG device which can acquire
a brain signal with a comparable accuracy to the large,
prohibitively expensive, medical grade systems previously used in
clinical settings.
[0011] Secondly, a design of the EEG sensors used permits the
acquisition of high quality data, despite a variety of ambient
noise artefacts. The unique shape of the electrodes permits a
signal to be read from the top of the head of the user without the
use of conductive liquid or gel. The mechanical integration of the
electrode in the headphones allows for a consistent contact with
the surface of the user's head, reducing movement artefacts.
Electronic pre-amplification, analog filtering and shielding reduce
ambient electromagnetic noise.
[0012] Thirdly, improved digital signal processing computational
algorithms has permit the isolation of valid brain signal amidst
the noisy data acquired by the EEG electrodes. The combination of
analog driven right leg circuits, analog and digital filtering,
digital remontage referencing, and blind source separation
algorithms yield a higher quality signal than was previously
possible.
[0013] Finally, the use of advanced machine learning classification
algorithms permits the identification of physical and mental states
of the user via the acquired and decomposed EEG signal. Modern
statistical information theory signal processing algorithms and
non-linear time-frequency transformations allows for the extraction
of unique features, which correlate with the desired physical and
mental states. Non-linear classifications algorithms use these
features to determine the real-time physical and mental state of
the user, via identification of feature patterns common to previous
users.
[0014] According to an embodiment, the low cost, easily accessible
over-ear headphones can be applied to provide the ability to
measure cognitive states from a consumer EEG device embedded in a
headphone, and use this information to give the user feedback in
real time on changes in their mental state, in order to condition
the user's brain to tend towards the desired state. Moreover,
monitoring of brain activity through EEG-enabled headphones permits
the user to visualize and interact with their level of
concentration in real-time, providing insight and tracking
previously unavailable outside of a clinical EEG laboratory.
Furthermore, it can be applied to many mental health ailments,
including but not limited to attention deficit disorders.
[0015] According to an aspect of the invention, there are provided
headphones comprising: [0016] earcups to be placed about ears of a
user; [0017] a headband linking the earcups and extending above a
head of the user; [0018] a flexible band distinct from the headband
such as to flex independently therefrom and secured below the
headband for contact with the head of the user; [0019] headband
electrode sockets formed within the flexible band for receiving
headband electrodes, the sockets having an electrically conductive
base.
[0020] According to an embodiment, the flexible band has a shape at
rest not conforming with a head by providing the flexible band with
a radius of curvature larger than a radius of curvature of a top
area of a human head.
[0021] According to an embodiment, the flexible band has a
flexibility which makes the flexible band deform under a weight of
the earcups to conform with the head of the user.
[0022] According to an embodiment, the flexible band has a shape at
rest characterized by a radius of curvature between 85 mm and 100
mm, and is made of a resilient material which under the weight of
the headphones, which is between 100 g and 1 kg, adopts a radius of
curvature between 70 mm and 85 mm.
[0023] According to an embodiment, the flexible band is deformable
under the weight of the earcups to conform with the head of the
user, while the headband does not substantially flex.
[0024] According to an embodiment, there are further provided
headband electrodes to be embedded in the sockets of the flexible
band and having a portion thereof protruding downwardly from the
flexible band.
[0025] According to an embodiment, the headband electrodes comprise
a flexible substrate and a plurality of legs extending therefrom
and protruding from the flexible band.
[0026] According to an embodiment, the each one of the legs has a
length between 4 mm and 9 mm.
[0027] According to an embodiment, the flexible substrate is both
electrically conductive and flexible such as to allow the legs to
change orientation with respect to the flexible substrate.
[0028] According to an embodiment, each of the headband electrodes
comprises a male connector to fit with a corresponding female
connector within the base of a corresponding one of the sockets to
hold the headband electrodes in the sockets and form an electrical
connection between the legs and the electrically conductive base
within the sockets.
[0029] According to an embodiment, the headband electrodes are
user-detachable from the base without having to dismount the
flexible band.
[0030] According to an embodiment, the flexible band comprises
three headband electrode sockets, one at a center of the flexible
band and two others provided more laterally with respect to the one
at the center.
[0031] According to an embodiment, the two headband electrode
sockets provided more laterally each are distant of about between
45 and 70 mm from the headband sensor at the center.
[0032] According to an embodiment, there are further provided
earcup electrodes on the earcups for contact with a head surface
behind an ear of the user, or on a rear surface of the ear of the
user.
[0033] According to an embodiment, the earcup electrodes comprise
conductive fabric.
[0034] According to an embodiment, the earcup electrodes comprise
an inward earcup electrode provided on an inward surface, where the
inward surface is directed toward the rear surface of the ear, on
at least one of the earcups.
[0035] According to an embodiment, the earcup electrodes comprise
an upper rear earcup electrode and a lower rear earcup electrode,
respectively located at an upper rear location and a lower rear
location on the inward surface of the at least one earcup.
[0036] According to an embodiment, the earcup electrodes further
comprise an outward earcup electrode provided at an outward
surface, where the outward surface is directed toward the head, in
a region of the mastoid when the headphones are worn.
[0037] According to an embodiment, the base in the headband
electrode sockets comprise a biasing element for adjusting a length
of protrusion of the headband electrodes downwardly from the
flexible band.
[0038] According to another aspect of the invention, there are
provided headphones comprising: [0039] a headband extending above a
head of the user; [0040] a flexible band distinct from the headband
and secured below the headband for contact with the head of the
user; [0041] removable headband electrodes, to be embedded in
sockets formed in the flexible band, and having a portion thereof
protruding downwardly from the flexible band.
[0042] According to an embodiment, the headband electrodes comprise
a flexible substrate and a plurality of legs extending therefrom
and protruding from the flexible band.
[0043] According to an embodiment, the each one of the legs has a
length between 4 mm and 9 mm.
[0044] According to an embodiment, the flexible substrate is both
electrically conductive and flexible such as to allow the legs to
change orientation with respect to the flexible substrate.
[0045] According to an embodiment, each of the sockets formed in
the flexible band comprises an electrically conductive base for
receiving the removable headband electrodes.
[0046] According to an embodiment, each of the headband electrodes
comprises a male connector to fit with a corresponding female
connector within the base of a corresponding one of the sockets to
hold the headband electrodes in the sockets and form an electrical
connection between the legs and the electrically conductive base
within the sockets.
[0047] According to an embodiment, the headband electrodes are
user-detachable from the base without having to dismount the
flexible band.
[0048] According to another aspect of the invention, there are
provided headphones comprising: [0049] earcups to be placed about
ears of a user; [0050] a headband linking the earcups and extending
above a head of the user; [0051] a flexible band distinct from the
headband and secured below the headband for contact with the head
of the user; [0052] headband electrodes embedded in the flexible
band; [0053] earcup electrodes on the earcups for contact with a
rear surface of an ear of the user.
[0054] According to an embodiment, the earcup electrodes comprise
conductive fabric.
[0055] According to an embodiment, the earcup electrodes for
contact with the rear surface of the ear are on an inward surface
of the earcup directed toward the rear surface of the ear.
[0056] According to an embodiment, the earcup electrodes for
contact with the rear surface of the ear comprise an upper rear
earcup electrode and a lower rear earcup electrode, respectively
located at an upper rear location and a lower rear location on the
inward surface of the at least one earcup.
[0057] According to an embodiment, there is further provided an
outward earcup electrode provided on an outward surface of the
earcup directed toward the head, in a region of the mastoid when
the headphones are worn.
[0058] According to another aspect of the invention, there is
provided a method for collecting EEG data, the method comprising:
laying onto a head of the user a headband of headphones, the
headband linking earcups; contacting with the head of the user a
flexible band distinct from the headband and secured below the
headband; letting the flexible band adopt a shape of a portion of
the head of the user under the weight of the earcups; contacting
headband electrodes embedded in the flexible band with a scalp of
the user; and collecting data from the headband electrodes.
[0059] According to an embodiment, there is further provided
collecting data from the earcup electrodes located on a surface of
the earcups.
[0060] According to an embodiment, there is further provided
identifying features in the collected data within time windows of
the collected data.
[0061] According to an embodiment, there is further provided upon
identifying the features, feeding the features to a machine
learning classifier to identify patterns in the features.
[0062] According to an embodiment, pattern identification comprises
determining a state of concentration.
[0063] According to an embodiment, there is further provided upon
identification of the patterns, feeding the patterns to a
meta-classifier to personalize pattern identification.
[0064] According to an embodiment, there is further provided upon
determining a state of concentration, providing a feedback to the
user, the feedback being dependent on the state of concentration as
determined.
[0065] According to an embodiment, providing the feedback comprises
determining a moment when to provide the feedback that is expected
to maximize an effect of the feedback to the user.
[0066] As will be realized, the subject matter disclosed and
claimed is capable of modifications in various respects, all
without departing from the scope of the claims. Accordingly, the
drawings and the description are to be regarded as illustrative in
nature, and not as restrictive and the full scope of the subject
matter is set forth in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0067] Further features and advantages of the present disclosure
will become apparent from the following detailed description, taken
in combination with the appended drawings, in which:
[0068] FIG. 1 is a front view illustrating headphones comprising
biosensors, according to an embodiment;
[0069] FIG. 2 is a schematic diagram illustrating the use of
headphones having sensors to provide feedback for concentration,
according to an embodiment;
[0070] FIG. 3 is a schematic diagram illustrating feedback to the
user, according to an embodiment;
[0071] FIG. 4 is a schematic diagram illustrating an architecture
of headphones having a plurality of different sensors, according to
an embodiment;
[0072] FIGS. 5A-5G are a front view, a first side view, a second
side view, a bottom perspective view, a bottom view, a side
perspective view and a top view, respectively, illustrating
headphones having EEG sensors, according to an embodiment;
[0073] FIG. 6 is a diagram illustrating spacing between lateral
electrodes on headphones and the head of a user, according to an
embodiment;
[0074] FIG. 7 is a diagram illustrating a headband of headphones,
according to an embodiment;
[0075] FIG. 8 is a front view illustrating a headband of headphones
comprises a lower headband or flexible band, according to an
embodiment;
[0076] FIGS. 9A-9B are diagrams illustrating the flexible band at
rest and independently deformed when being worn, according to an
embodiment;
[0077] FIG. 10 is a diagram illustrating a flexible band of
headphones, according to an embodiment;
[0078] FIG. 11 is a close-up perspective view illustrating a limit
of movement of armbands to avoid impacting the flexible band of
headphones, according to an embodiment;
[0079] FIG. 12 is a diagram illustrating a flexible band of
headphones with electrodes protruding therefrom, according to an
embodiment;
[0080] FIGS. 13A-13D are diagrams illustrating a deformation of the
flexible band of headphones, according to an embodiment;
[0081] FIGS. 14A-14B are perspective views illustrating a base for
the headband electrodes, according to an embodiment;
[0082] FIG. 15 is a perspective view illustrating a headband
electrode, according to an embodiment;
[0083] FIGS. 16A-16B are side views illustrating a headband
electrode at rest and deformed under a force, respectively,
according to an embodiment;
[0084] FIG. 17 is a perspective view illustrating an armband for
holding the earcups, according to an embodiment;
[0085] FIG. 18 is a perspective view illustrating a pivot member
within an armband for holding the earcups, according to an
embodiment;
[0086] FIG. 19 is a perspective view illustrating a pivotable
earcup, according to an embodiment;
[0087] FIG. 20 is a side view illustrating the inclination of the
earcup, according to an embodiment;
[0088] FIG. 21A is a side view illustrating definitions of a shape
of the earcup, according to an embodiment;
[0089] FIG. 21B is a top view illustrating the inside of an earcup,
according to an embodiment;
[0090] FIG. 22 is a side view illustrating electrodes on an outward
surface and an inward surface of an earcup, according to an
embodiment;
[0091] FIG. 23 is a side view illustrating electrodes on an outward
surface and an inward surface of an earcup, according to another
embodiment; and
[0092] FIG. 24 is flowchart illustrating a method collecting data
with EEG sensors and extracting meaningful information from the
data, according to an embodiment.
[0093] It will be noted that throughout the appended drawings, like
features are identified by like reference numerals.
DETAILED DESCRIPTION
[0094] Many people who work in stationary and intellectually
demanding jobs express that they have difficulty concentrating for
extended periods of time. The inability for humans to concentrate
for a long time has been well quantified, and is understood to be a
severe problem in many work environments. Similarly, many people
diagnosed with attention deficit disorder and attention deficit
trait express a physiological inability to concentrate for extended
periods of time. The rate of diagnosis of attention deficit
disorder is increasing, while human performance on sustained
attention tasks decreases.
[0095] The present invention integrates EEG sensors into over-ear
headphones which are both usable as typical headphones, while being
adapted for providing a high-quality contact of the sensors with
the user's skin for data collection. The EEG sensors can be used to
help users monitor, track, and improve attention, alertness, and
concentration while they work. Other applications requiring the use
of EEG sensors for electrical data collection on a user's head can
be implemented using the presently described headphone which
comprises sensors with high-quality contact that is well maintained
over time.
[0096] Applications such as concentration monitoring can be
advantageously complemented with feedback reactions, such as those
implementing the principle of neurofeedback, or similar feedback,
among other features. The pair of over-ear headphones, can output
collected data to a computing system implementing machine learning
techniques to deliver neurofeedback for improving concentration.
Furthermore, while neurofeedback is typically a deliberate task
that requires full attention and the help of a trained clinician,
the present invention permits neurofeedback to take place in any
environment, while the user performs their own work. This permits
the user to get the benefits of a neurofeedback-like type of
feedback, while working on any task they please. One may thus more
accurately refer to this feedback as biofeedback based on a user's
cognitive state, and in this sense similar to neurofeedback. Other
types of feedback (which are not neurofeedback) can be performed,
such as reminding people to get back to task. Any other application
requiring the use of EEG sensors for electrical data collection on
a user's head can be put into effect while the user is working on a
task or moving, since the headphone comprises a flexible band
beneath the headband, as well as a particular sensor design, that
allows the EEG sensors to make a high-quality contact with the
user's scalp that is well maintained over time.
[0097] Computational algorithms can be applied to the data
extracted from the signals coming from the variety of sensors,
including but not limited to EEG, to extract information which can
be inputted to a machine learning classifier in order to infer the
mental and physical state of the user in real time. Other sensors
can include, among others, a heart rate sensor, a galvanic skin
response sensor, a body temperature sensor, an accelerometer, a
gyroscope, etc.
[0098] According to an embodiment, the inferred mental and physical
state can be used to allow the user to track, monitor, and improve
their attention, alertness, and concentration in real time. One may
also monitor features defined as engagement, cognitive workload,
executive functioning, sustained attention, mind wandering,
distraction, etc. This is accomplished via visual, auditory, and
physical feedback to the user of their current physiological state
in real-time, based on the principle of biofeedback. This feedback
is provided while the user accomplished any desired task, in
contrast to the active participation currently required by typical
neurofeedback sessions.
[0099] The headphones are designed to be used in a primarily
stationary setting, although typical movements implied by desk work
is permitted, while the user is performing an intellectually
stimulating task. The headphones are targeted towards desk workers
who wish to improve attention during their workday.
[0100] Statistical analysis of the users mental and physical state
across time may be provided. This analysis permits quantification
the inferred efficacy of their workflow, monitoring of stress and
engagement levels, changes, and improvements over time.
[0101] Suggested habit changes may be given to the user based on
the historical trend of their inferred mental and physical state.
These suggestions may be given in real-time in the form of
feedback, or in aggregate before or after a session. The effect of
changes in the user's habits in response to suggestions, feedback,
changes in workflow, and changes in music played by the headphones
may be used to modify the predictions and suggestions given.
[0102] Integration with wearable devices, software programs, and
other monitoring tools may allow for more customized and relevant
feedback. The aggregation of several input sources, i.e.,
biosignals, which are electrical data collected from biosensors on
the body, may be used to improve the accuracy of the prediction
algorithms used to infer the mental and physical state of the user.
The user experience, including but not limited to the current music
and the feedback given, may change as a function of the task being
performed by the user. User-specific preferences may be used to
customize the experience delivered by the present invention,
through modification of the audio, visual, and physical feedback
delivered.
[0103] FIG. 1 illustrates a first embodiment of the headphone.
Another embodiment will be described further below in relation with
FIGS. 5A-5G. Some features described in relation with FIG. 1 should
not be viewed as exclusive to the embodiment of FIG. 1 as they can
also be applied to the other embodiment described in relation with
FIGS. 5A-5G.
[0104] As shown in FIGS. 1-2, the headphone 10 uses a plurality of
electroencephalographic and biopotential sensors 11-18 to measure
and record electrical potentials originating in the brain.
Electrical potentials originating from other sources in the body,
such as the heart, the eyes, or muscles, can be measuring by
providing sensors at the appropriate locations on the surface of
the body. In this case, where electrical potentials originating
from the brain are the primary source of data, the sensor
electrodes 11-18 are embedded in an upper band 21 of the headphone
10, measuring voltage on the scalp 20. This information is
processed and relayed to a computer 30, which interprets the
signals to determine the current state of the brain 40. Among other
states, the computer detects the user's level of attention and
alertness 40, which are used to predict the user's concentration or
distraction 50 with respect to their given task.
[0105] The voltage measured by the electrodes 11-18 is amplified
22, filtered 23, and passed through an analog-to-digital converter
24. According to an embodiment, the signal is then transferred to
the computer 30 via Bluetooth, Wi-Fi, or a similar protocol. In the
computer 30, the signal is pre-processed in order to remove noise
90. Several features can then be calculated from the signal, using
a variety of statistics and signal processing techniques 70.
[0106] According to an embodiment, this information is fed into a
machine-learning model, which predicts the state of concentration
of the user 50. This prediction can be used to send feedback to the
user 60 of their state of concentration in real-time. The mental
state of the user will be actively influenced (based on alarms,
reports, etc.) or passively influenced (by subtly changing volume
of the music played by the headphone) by this feedback, improving
their concentration over time.
[0107] As shown in FIG. 3, the feedback 60 described above will be
delivered in the form of a distinguishable notification, the
purpose of which is to alert the user of their changed mental state
and bring the user's attention back to their task. This will be in
the form of an auditory modulation 61--an increase or decrease in
the volume 611, or a deliberate change in the sound played through
the headphones 612. Visual feedback 62 on a computer, mobile
device, or integrated light may also be delivered, via modulation
of the visuals 62 on the screen. Other forms of feedback include
vibration 63, or changes in the functionality of certain headphone
features 64 (changing noise cancelling, or turning on/off
notifications) or other similar application-level changes. Several
forms of feedback may be combined, in order to change the user
experience. The feedback may vary in style, intensity, and
frequency depending on a variety of user and setting-specific
features.
[0108] As shown in FIG. 4, additional sensors embedded in the
headphones to detect a variety of physiological measurements 110
including heart rate 111, skin conductance 112, and body
temperature 113. Ambient conditions 120 such as noise levels 121
and ambient brightness 122 are also recorded. The computer 30 uses
these measurements in addition to the brain activity when
predicting attention and alertness, as well as when determining
whether to send feedback. The individual combination of sensors and
algorithms used in the determination of the user's mental state and
in the delivery of feedback will be customized to the user's
personal physiology, preferences, daily patterns, and response to
previously given feedback.
[0109] Again, as shown in FIG. 4, the system comprises of
electrodes 11-18, of passive or active nature, whereas active
pertains to the proximity of an amplifier to the source of the
signal. The electrodes 11-18 should be dry electrodes, which are
better suited for use with headphones. The electrodes 11-18 will
record brain signals (EEG) 161, muscular activity (EMG) 162, ocular
activity (EOG) 163, heart activity (ECG), or any combination of the
above.
[0110] The headphones 10 may also incorporate noise-cancelling
130--either passive or active--in order to change and improve the
user's work environment. An activity light notifying 140
surrounding people that the user is currently busy may be included,
in order to prevent disturbances during desired times. In addition,
the headphones may incorporate one or several microphones 150,
which may be used by the user to record and communicate, while also
being used to monitor the external noise level providing insight
for better noise cancelling and prediction of concentration.
[0111] The headphones 10 are anticipated to be used in a work
environment, in order to reduce distraction and improve
productivity during a task. The user will be able to customize the
feedback experience to the work currently being done. Personal
profiles, modulated as a function of the user's preferences and
needs, will allow for a catered experience as a function of the
desired state.
[0112] Using a similar methodology, several other mental or
physical states may be predicted via classification of the
combination of signals acquired from the headphone's sensors. These
may include but are not limited to stress, sadness, anger, hunger,
or tiredness. Likewise, the presence of neurological disorders such
as epilepsy, anxiety disorder, and attention deficit disorder may
be predicted in a similar fashion.
[0113] The system may modify human behavior through the delivery of
brain-state inspired feedback. These modifications will yield
short-term changes in behavior through immediate user response to
the feedback provided. An example of this is returning attention to
the desired task when notified of the current state of distraction.
These modifications can also induce long-term neurophysiological
changes due to the user's subconscious response to the feedback
provided. An example of this is a subconscious conditioning of the
neurological sustained attention system, improving the ability to
sustain focus for long durations.
[0114] Trends and analytics performed on the recorded bio-signal
data provide information on the user's mental and physical state,
and allow for prediction of user behavior and their optimal
states.
[0115] The system uses a combination of one or more sensors to
measure bio-signals and ambient conditions, in order to measure and
infer the mental and physical state of the user. These sensors
include but are not limited to electrodes, temperature probes,
accelerometers, pulse oximeters, microphones, and pressure
transducers.
[0116] The shape and structure of the electrodes are such that they
have the capability of passing through the hair and making direct
contact with the skin. Examples or embodiments are legged sensors,
comb-like structures, flat plates, peg arrays and spring-loaded
pegs. The shape and material choice ensure a consistent contact
with the skin, minimizing connection impedance.
[0117] The system may include a microphone that monitors external
ambient noise. This information may be used to modulate the
feedback, the music, or the noise cancellation as a function of the
level of environmental distraction predicted from the measured
ambient conditions. The ambient sound may integrate with the sensor
data in order to provide more accurate prediction of the user's
mental and physical state. Customizable preferences, including but
not limited to the choice of music played through the headphones,
may be modulated as a function of the environmental noise. White
noise, binaural beats, instrumental music, or user-defined
preferences may be used alone or in combination in order to create
an ideal work environment for the user. Changes in predicted
concentration as a function of the music played may be used to
improve focus prediction and feedback delivered.
[0118] The system may include passive or active noise isolation.
High-density foams, leather, and other materials may be placed
around the ear cup in order to isolate the user from external
environmental noise. Ambient sound monitoring via the microphone
may be used to determine which sounds should be attenuated and
which should be amplified.
[0119] Body temperature fluctuations may be monitored, and used to
improve prediction of the user's mental and physical state. Body
temperature may be used to detect long-term trends in user
productivity, related to circadian rhythms, energy levels, and
alertness. This information may be used to improve the feedback
delivered to the user.
[0120] Recording of heart rate can provide additional information
on body states, including attention and stress levels. Pulse
oximetry, balistocardiogram, electrocardiogram, or other
substitutable technology may be used for measuring heart rate near
the ear or scalp. Analytics performed on heart rate measurements
may be used to infer physiological characteristics, including but
not limited to heart rate variability, R-R distance, and blood flow
volume. These computed physiological characteristics may be used to
modulate the feedback delivered to the user, in the form of
delivering suggestions for improving concentration.
[0121] The system may include sensors in the ear cup, touching the
ears or in the area around the ears, for the purpose of recording
bio-signals.
[0122] The system may include a mechanism for preventing unwanted
mechanical movement of the headphones with respect to the head. A
possible embodiment of this mechanism is a pad which contacts with
the user's head and locks onto the bone structure of the skull,
preventing motion of the headphones with respect to the scalp. This
mechanism may also be used to promote positioning repeatability of
the headphones and sensors on the head.
[0123] According to an embodiment, each electrode is embedded in a
stabilizing mechanical structure, designed to reduce cable
movement, external electrical noise and electrical contact breaks.
The stabilizing structure keeps the electrodes in consistent
contact with the surface of the user's head during movement.
[0124] According to an embodiment, the system comprises an
adjustment mechanism, allowing the user to better position the
headphones on their head. The mechanism may allow for radial
adjustment of the shape of the headphones, adapting for variations
in users' head width. The mechanism may allow for adjustable
vertical positioning of the sensors, in order to evenly distribute
the downward force and ensure proper contact of the electrodes.
[0125] Where the system interfaces with the side of the head,
leather, fabric, or memory foam may be used for comfort. The
material contact interface may be tuned in order to prevent
movement of the headphones with respect to the user's head, as well
as to dampen vibrations.
[0126] Electrodes along the top band may be static, or attached to
a moving mechanism that allows the electrodes to retreat completely
into the band when not in use. The movement of the electrodes may
be controlled via a manually actuated interface, or automatically
via the placement of the headphones on the user's head. According
to an embodiment, the electrodes are removable, at which point the
biosensor headphone becomes a normal headphone. For example, the
electrodes can be made removable using a snap-fit connector, or a
connector with a male portion engaged in a female portion and held
therein with frictional forces.
[0127] The system may include a rotational mechanism along the axis
connecting the user's ears, allowing the top band to be rotated to
contact the forehead, the back of the head, the neck, or other
parts of the scalp. This would permit positioning the sensors at
other key locations on the head to perform data collection from the
prefrontal cortex, the parietal lobe, the occipital lobe, or the
neck, for example.
[0128] According to an embodiment, the system has the capability of
playing an external audio stream over-the-air from a computer or
mobile device while simultaneously transferring signals recorded
from the headphones to said device. The data-transfer protocol may
take place via Bluetooth, Wi-Fi, RF-wave, or other similar wireless
protocols.
[0129] The system may have an activity light that responds to
current brain states. This light notifies other parties of the
user's current mental or physical state. One such use is to notify
nearby parties that the user is currently busy or concentrated, so
as to prevent disturbances.
[0130] An alternative embodiment may include the use of this
technology as an add-on to existing headphones, connecting to the
top band of the headphones and functioning independently of the
headphones. An alternative embodiment may also include a
multi-purpose band that may be used around the neck, arm, head,
leg, or other body part.
[0131] The system shall be classified as a computer or
computational device, for it not only plays music, but has the
capability of recording vital signs and bio-potentials, processing
them, and generating an output, independently of whether it is
connected to a computer or phone device.
[0132] Now referring to FIGS. 5A-5G, there is shown an embodiment
of the headphone 10 according to various views. The embodiment of
the headphone 10 of FIGS. 5A-5G comprises a particular design of
headband electrodes 310, embedded in a flexible band parallel but
distinct from the headband, and earcup electrodes 360. Other
features, such as music, noise-canceling, microphones, other
sensors and add-on features of the headphones described above in
relation with FIGS. 1-4, as well as feedback features, are also
applicable to the embodiment of the headphone 10 of FIGS. 5A-5G and
will not be repeated.
[0133] According to this exemplary embodiment, the headband 200 has
a flexible band 210 secured thereto and in which is embedded at
least one EEG sensor, or biosensor, i.e., a sensor or electrode
measuring electrical activity on the body. According to a preferred
embodiment, there are embedded three EEG sensors, or biosensors, in
the flexible band 210. Additional EEG sensors can be provided on
the earcups 400, e.g., by making a portion of the foam forming the
earcup 400 conductive.
[0134] As discussed above, typical headbands from usual headphones
are not designed to bear EEG sensors. As a result, simply
integrating EEG sensors to an existing headphone of a given shape
is not likely to offer interesting results in terms of electrical
contact between the EEG sensors located thereon and the skin on the
person's head, i.e., the scalp.
[0135] The embodiment shown in FIGS. 5A-5G addresses the issue of
suboptimal contact between headphone-mounted EEG sensors and the
scalp by providing the EEG sensors on a flexible band distinct
(i.e., separate) from the headband and secured to the headband. The
flexible band is provided below the headband and is made of a
material that renders such band flexible up to the point that the
flexible band generally adopts the shape of the head of the user
while taking into account that the EEG sensors protrude from the
flexible band toward the scalp.
[0136] The issue of having a headphone set not conforming the
user's head is shown in FIG. 6. Getting sufficient signals from
electrical activity in the brain requires placing electrodes at
different locations on the person's head, and not only at the top
of the head. In other words, electrodes need to be placed at
locations away from the top center of the head, i.e., at more
lateral locations on the head as shown in FIG. 6. This requirement
for electrode placement at more than one location including
locations away from the top center (while being within the reach of
the headband) creates a strict requirement on the headband shape if
one wants to achieve high signal quality and reliability from the
sensors at these locations. According to an embodiment, the lateral
sensors are distant from the center sensor from about 65 mm (i.e.,
half the head arc length of a standard person), or between 60 mm
and 70 mm, or between 45 mm and 70 mm, or between 45 mm and 80 mm.
These distances allow electrodes to lie at the C3 and C4 locations
according to the international 10/20 standard.
[0137] Prior art headphones with sensors failed to achieve high
signal quality and reliability from the sensors at locations away
from the top center. Typical headbands for headphones were used for
these applications, meaning that the purpose of the headband was
solely to mechanically link and electrically connect the earcups,
while offering a support, preferably a comfortable one, when being
laid on the user's head.
[0138] However, as discussed above, the purpose of the headband of
the present invention, in addition to those of the prior art, is to
provide a structure on which the sensors are mounted. These sensors
need to be adequately located, maintained at their intended
location, and put into contact with the scalp while having a proper
contact (to have a high-quality signal) that is maintained over
time (so the signal is reliable enough for eventually extract
information therefrom).
[0139] Moreover, in addition to the main portion of the headband
200, there is provided a flexible band 210, which extends in a
shape substantially like a central portion of the headband and is
secured under the headband 200 to conform with the user's head when
being deformed under the weight of the headphones 10 when being
worn.
[0140] Each of the headband electrodes is secured at a bottom of
the flexible band 210, or lower headband. The flexible band 210
serves the purpose of adjusting the position of each electrode when
the headphones are being worn, such that a contact is maintained
with the user's head independently of the position of the
headband.
[0141] This is done by providing the flexible band 210 with a shape
and a material having a flexibility which ensure that upon laying
the headband on the user's head, the weight of the headband with
the earcups at both ends pushes the flexible band 210 along the
surface of the head, including for areas away from the top center
of the head, as shown in FIG. 7. However, the flexible band 210
should keep a rounded shape at rest and in use and simply bend or
flex when being used, as it should still have some rigidity
(although it should be less rigid or stiff than the upper headband
200). It means that the flexible band 210 should not be confused
with a fabric or an elastic band, which would have some drawbacks.
Notably, if the flexible band 210 was a fabric or an elastic band,
it would not provide proper support for the electrodes, it would
not allow them to be easily removable with a snap-fit connector, it
would be fragile (i.e., easy to tear), it could expose the inner
parts such as cabling, and thus it would not be suited for a
consumer product.
[0142] The flexible band 210 is shown in FIG. 8 as being separate
from the headband main structure and extending under it. The
flexible band is made of any material flexible enough to deform
under the weight of the headphone. There are for example many
plastics that can deform when a weight corresponding to a few
hundred grams is applied on the object. The force is applied by
having the central portion of the flexible band 210 applied on the
top center of the head and conform therewith, while the lateral
portion of the flexible band 210 do not touch the head. If there is
no gravity, the flexible band would be at rest, as shown in FIG.
9A, and remain in this position. However, when the headphones 10
are being worn, and as shown in FIG. 9B, the gravity pulls down the
sides of the flexible band 210 (those closer to the earcups and
originally not in contact with the head). These sides of the
flexible band 210 are those deformed by gravity and brought down
along the surface of the head, to which they conform, at least
approximately. The use of a flexible band 210, which has greater
flexibility than prior art head bands, and which is closer to the
surface of the head, allows a closer and more conforming contact
between the flexible band 210 and the head of the user for
locations that are more lateral compared to the top center of the
head.
[0143] The flexible band 210 thus better conforms to the shape of
the head than prior art headbands. Electrodes are thus provided in
the flexible band 210 and protrude downwardly from the flexible
band to reach the scalp of the user. As discussed further below,
additional sensors can be placed on or in the earcups. However, the
flexible band 210 comprises the sensors that aim at touching the
scalp.
[0144] According to an embodiment, there are three sensors, one
being located at a center of the flexible band 210 in order to be
located on the top center of the user head, and two other lateral
sensors located away from the center of the flexible band 210,
preferably symmetrically from the center, in order to reach lateral
locations on the head as discussed above (those for which the
presence of the flexible band 210 ensures better and
longer-maintained contact). This is shown in FIGS. 5A-5G.
[0145] Now referring to FIG. 10, the headband 200, or upper
headband, can be sized to ensure that when deformed (along with the
flexible band 210 underneath) under the weight of the headphones
10, the headband 200 (along with the flexible band 210 underneath)
substantially adopts the shape of the surface of the head on which
it lies.
[0146] Now referring to FIG. 11, there are shown lines that
illustrate the maximum position of the earcups holders along the
headband. Indeed, a stopper needs to be provided by the sliding
rail in which the earcups holders are provided to ensure that the
earcups holders cannot be retracted along the headband 200 up to a
point where they would hit the flexible band 210 and damage it.
[0147] Now referring to FIG. 12, the flexible band 210 can be sized
to ensure that when deformed under the weight of the headphones 10,
the flexible band 210 substantially adopts the shape of the surface
of the head on which it lies, and has its electrodes protrude at a
protruding distance which is consistent with standard hair
thickness and is not too short such as to prevent contact with the
scalp, or too long which would put all the weight pressure into the
legs of the electrodes and thus be uncomfortable. According to an
exemplary embodiment, the flexible band 210 has a thickness of
about 14 mm, or between 12 mm and 16 mm, or between 10 mm and 18
mm. According to an exemplary embodiment, the flexible band 210 has
an arc length of about 196 mm, or between 192 mm and 200 mm, or
between 180 mm and 212 mm.
[0148] The flexible band 210 is flexible in that it can adopt a
variety of radiuses of curvature. The upper headband 200 is more
rigid and preferably has a larger radius of curvature, but its
radius can change too under the application of forces. According to
an exemplary embodiment, the radius of the upper headband 200 can
vary from a minimum of about 107 mm to a maximum radius about 136
mm. Other variations and ranges are possible, for example the
minimum radius can be in the order of 80 mm to 110 mm, and the
maximum radius of curvature can be in the order of 120 mm to 160
mm.
[0149] At rest, the flexible band 210 should have a radius of
curvature chosen between 80 mm and 100 mm, or preferably between 85
mm and 100 mm, or more preferably between 85 mm and 97 mm, so that
the flexible band 210 has a radius of curvature larger than that of
most human heads (e.g., 80 percentile), measured at their top area,
so as to not conform with a user's head when at rest. Upon being
laid on the user's head, the weight of the earcups 400, combined to
the force of the top of the end on which the flexible band 210
presses, will force the flexible band to deform. Since it is
distinct from the upper headband 200 (although they can look to be
together by being housed with an envelope or a protecting fabric),
the flexible band will deform so as to conform with the head of the
user, thereby adopting a radius of curvature below 85 mm, and
preferably below 80 mm, but above 70 mm, as allowed by the
resilient material forming the flexible band 210 under the effect
of the weight of the headphones (most of it from the earcups and
arms) which weights a few hundred grams (realistically above 100 g
and below 1 kg, and more realistically between 150 g and 500 g, and
probably between 200 g and 400 g, more probably about 300 g).
[0150] Now referring to FIG. 13A-13D, there are shown measurements
of the deformations undergone by the flexible band 210 in relation
with the discussion above regarding the radiuses of curvature. It
is shown that the flexible band 210, or lower headband, bends
independently from the upper headband 200. The flexible band 210
should be larger than most heads at rest. When laid on a head, the
weight of the earcups 400 pulls down the ends of the flexible band,
which transitions from a large radius of curvature to a small
radius of curvature, where the large and small radiuses were
discussed above.
[0151] Now referring to FIG. 14A-14B, there is shown an embodiment
of a base 315 for the headband sensors 310. The base 315, or
dynamech, comprises a body 316 onto which the electrode is secured,
and a spring 318 or another biasing means (e.g., any piece of
material with elastic deformation properties, or an electromagnetic
biasing device) that ensures the electrodes can protrude more or
less depending on circumstances. The spring 318 is useful for
adapting the protruding distance of the electrodes outside the
flexible band 210. A female connector 319 is being formed in the
base 315 for mechanically receiving (e.g., in a snap-fit
relationship) and electrically connecting a male connector 311 of
the headband sensors 310. If a snap-fit connection is made between
the pin and the bore, then the headband sensors 310 can be
removably secured (i.e., insertable and removable by the user) in
sockets formed within the flexible band 210, each one of the
sockets having the base 315 at their bottom. The base 315 is then
electrically connected to electronics within the headphone 10 for
actual data collection.
[0152] The purpose of the base 315 is to ensure that the electrode
is adjusted to the right height with respect to the flex band, in
order to penetrate the user's hair and make contact with their
scalp. The secondary purpose is to transfer the signal from the
electrode to the active PCB.
[0153] In order to penetrate the hair of the users, the electrode
legs protrude below the flex band. Since the thickness of people's
hair varies from person to person, the length by which the
electrode protrudes below the band must vary. User testing
confirmed that the compressed thickness of people's hair with
respect to the top of their head varies from 0 mm (bald) to 6 mm
(thick hair). The base 315 adjusts the height of the electrode legs
by allowing the electrode to retract into the band by up to 6 mm
(which is thus the maximum protrusion length). This is the primary
requirement of the base 315. The spring 318 allows the electrode to
retract into the band when force is applied by the user's head.
When the headphones are worn, the spring would automatically
compress to the appropriate height for the given user's head.
[0154] The secondary requirement is that the base 315 must conduct
the signal from the electrode (which measures the EEG from the
user's scalp) to the active PCB. This may be accomplished by the
base 315 itself, or by a separate conductor part.
[0155] Now referring to FIG. 15, there is shown an embodiment of a
headband electrode 310 as used on the flexible band and to be
applied onto the scalp of the user.
[0156] According to an embodiment, the headband sensors 310, or
electrodes, comprise a flexible substrate 320 to which legs 340 are
attached. The flexible substrate 320 can be made of either polymer
or a thin portion of metal. Using a polymer, or a thin surface of
metal, ensures that the flexible substrate 320 is flexible,
especially more flexible than the legs 340. It means that under the
weight of the headphone (which normally has a mass in the order of
magnitude of a few hundred grams), when the headband sensor 310
contact and urges on the user's head, the legs 340, which are more
rigid (or less flexible) than the flexible substrate 320, will
spread (i.e., the rod-shaped leg will change orientation compared
to the original orientation which is perpendicular to the flexible
substrate 320) while not particularly changing shape. This spread
means that the base of the legs 340 is allowed to change
orientation, i.e., that the flexible substrate 320 holding the
proximal end of the leg is deformed under such a force to put into
effect the independent change of orientation of each one of the
legs 340. The flexible substrate 320 offers some symmetry and has a
diameter of about 16mm, or between 14 mm and 18 mm, or between 12
mm and 20 mm. FIGS. 16A and 16B illustrate, for an exemplary
two-leg sensor, a pair of leg in an original position and in a
spread position, respectively. A male connector 311 extends from
the flexible substrate 320 in a direction contrary to that of the
legs 340.
[0157] According to an embodiment, the legs, or pins, are made of
metal, to be both electrically conductive and preferably rigid
(i.e., not substantially flexible in comparison with the flexible
substrate 320). The legs of the electrode can be gold-plated, or
plated with or made of other materials such as silver,
silver/silver chloride, tin, stainless steel, or platinum, in order
to provide a corrosion-free contact interface with the skin, since
the scalp is a high-salt environment. The legs fit through the
user's hair to maintain contact with the user's scalp, while the
flexible substrate acts as a spring mechanism, or adaptive base for
the legs 340, to equalize the force between the legs 340 and allow
each one of them to undergo an independent angular movement (i.e.,
spread) with respect to the flexible substrate 320, and maintain
contact for each one of the legs 340 with the scalp in response to
movement of the headphone 10 on the user's head.
[0158] The legs 340 of the headband electrodes 310 have a diameter
which is small enough to fit through the user's hair. According to
an embodiment, there leg has a diameter of about 2 mm, or between
1.8 mm and 2.2 mm, or between 1.5 mm and 2.5 mm. The bottom (i.e.,
distal end with respect to the flexible substrate 320) of each leg
is curved in such a way as to maximize the contact surface area of
the electrode on the user's skin. The legs 340 may be either rigid
or flexible. According to an embodiment, they are rather rigid and
have a stiffness of about 50 g/mm. The electrode legs 340 may move
independently from each other, in order to allow for a consistent
contact on an irregular surface.
[0159] The length of the legs 340 should be slightly longer than
the desired protrusion length of the legs. For example, a length of
7.4 mm is appropriate to provide the protrusion length of maximum 6
mm. Otherwise, a length between 6 mm and 8 mm, or between 4 mm and
9 mm, or between 2 mm and 9 mm, would be appropriate and provide a
protrusion length of about 1.5 mm shorter.
[0160] According to an embodiment, a printed FPC can be used as the
conductive substrate, since it provides the required flexibility
while maintaining the ability to conduct the signal through.
Alternative designs may instead use a copper plate, conductive
rubber, steel, or any comparable conductor. The legs can be
soldered to the substrate, but any comparable electrical connector
is suitable.
[0161] According to an embodiment, the electrode is replaceable by
the user. As such, the electrode should be easy to insert or remove
from the base 315, inserting and ensuring an adequate electrical
connection. The electrode should also be stable enough to be
manipulated by hand without breaking or plastically deforming. A
friction connector can be provided with the base 315, for example a
connection similar to an RCA cable, i.e., a rigid conductive pin
sliding into a flexible insert. Any alternative connector is
equally suitable, so long as the resulting fit in tight enough to
prevent the electrode from bending at the connector joint, or
falling out of the socket formed within the flexible band 210.
[0162] According to an embodiment, the headphone 10 provides
additional sensors, namely earcup sensors 360 on the earcup 400,
since collecting data from this region by the ears may be useful in
some circumstances. The earcup sensors 360 comprise a conductive
material (conductive fabric or polymer, or metal) embedded in the
inside of the earcup foam, which can be sewn thereto. The earcup
sensor 360 is located at a location on the earcup 400 which allows
for making a mechanical (and thus electrical) contact with the back
of the user's ear, near the mastoid. The earcup sensor 360 may also
comprise a rigid or semi-rigid protrusion on the inside of the
earcup 400, which contacts the top or back of the user's ear while
the headphones 10 are worn.
[0163] As shown in FIGS. 22 and 23, illustrating an inward surface
(left) and an outward surface (right) of an earcup, where the
outward is the portion of the earcup that contacts the head of the
user, and in inward is directed toward a rear surface of the ears.
As shown in FIG. 22, the earcup sensors 360 can be provided on a
rear surface on at least one earcup 400, i.e., a dual back
arrangement, where a first earcup sensor is located at an upper
rear location and a second earcup sensor is located at a lower rear
location on the inward side of the earcup 400, where they are
expected to contact a similarly located area of the rear surface of
the ear. Alternatively, as shown in FIG. 23, there can be provided
earcup electrodes 360 on the two sides of at least one of the
earcups (back and front, or outward/inward arrangement). This
second embodiment covers a greater total surface area but
introduces greater complexity as a conductive fabric needs to be
sewn on the inward area of the earcups, where it will be in contact
with the user head (i.e., the mastoid area), and also exposed to
damage. Moreover, outward earcup electrodes 360 can be less
performant if the user has hair by the mastoid area, where such an
electrode is to be in contact. Inward earcup electrodes 360 are not
affected by hair, as there is none on the rear surface of the
ear.
[0164] The earcup 400 curves around the user's ear (i.e., it is
circumaural), maintaining contact with the back of the mastoid.
According to an embodiment, the earcup comprises foam. The earcup
400 is smaller than typical prior-art circumaural ear cups (i.e.,
the type of earcup that surrounds the ear), which typically do not
contact the user's ear. It is also larger than typical prior-art
on-ear cups, which compress the ear and do not surround it. The
earcup 400, according to an embodiment of the invention, thus has a
size that would be considered, in the prior art, as an in-between
situation which would not be desirable, whereas it is used in the
present headphone 10 to ensure proper contact between an inside
portion of the earcup and an outside portion of the ear where
electrical contact by the sensor 360 may be desirable.
[0165] The armband or earcup holder 450 is shown in FIG. 17.
According to an embodiment, the earcup holder 450 may comprise a
sliding rail 455 or any other means by which the overall length can
be adjusted up to certain limits by raising or lowering the
earcups. Compared to the prior art, the sliding rail should
comprise a stopper that prevents the earcup holder to impact the
flexible band 210. As shown in FIGS. 18-19, the earcup holder 450
can comprise a pivoting member 456 which can comprise for example
two pivots, such as a mastoid pivot and a sagittal pivot, allowing
rotation of the earcup 400 along these axes for better contact of
the earcup sensors 360 with the ear of the user when being
worn.
[0166] According to an embodiment, the earcup 400 is asymmetric,
such that a small lip tucks behind the user's ear when it is being
worn. The radius of this lip can be chosen to match the gap between
the user's ear and the mastoid, caused by the auriculocephalic
angle of the ear, as shown in FIG. 20. The foam should contact the
user's ear primarily at the back of the ear. Contact along the top
of the ear is permitted, so long as the applied pressure does not
cause discomfort, but is not necessary. The radius of the point of
contact between the foam and the ear can be about 5 mm, to ensure
that contact is made across a range of ear shapes.
[0167] FIGS. 21A-21B illustrate the shape of the foam piece of the
earcup, and further illustrate that the foam piece of the earcup is
shaped to reach the region behind the ears. According to an
embodiment, the inner width is about 30 mm, the outer width is
about 68 mm, the inner height is about 60 mm and the outer height
is about 98 mm.
[0168] There is now described electronic filters which can be
advantageously provided in an embodiment of the headphones to
filter noise and eventually enhance signal quality for later
analysis.
[0169] According to an embodiment, each electrode (headband
electrodes 310 and earcup electrodes 360) has a direct electrical
connection to a high-impedance voltage follower circuit, which
buffers the incoming EEG signal. The buffer circuit is subsequently
connected to a series of passive and active filter circuits, which
de-noise the signal, and then to a high-gain amplification circuit.
Finally, each channel passes through an analog to digital
converter, before being sent to the computer via Bluetooth or USB.
A protection circuit can be added to protect the circuitry from
electrostatic discharges by limiting current below 1 .mu.A.
[0170] According to an embodiment, the printed circuit board (PCB)
layout comprises components which implement several preconditioning
techniques optimized for EEG signals. These can include, without
limitation: [0171] using oxygen-free copper planes; [0172]
shielding components with a copper cover, which can passive or
active during the signal preconditioning; [0173] choosing materials
for the passive components for their specific properties, among the
following:
[0174] a. silver mica for active filter capacitors;
[0175] b. tantalum and metal film for power supply decoupling;
and
[0176] c. metal film or wire wound resistors for noise reduction;
[0177] PCB traces use a combination of copper-gold; copper silver;
copper silver and gold in specific percentages to improve
signal-to-noise ratio.
[0178] Within the headphone 10, different components can be added,
during assembly, in order to limit noise interference during data
collection by the sensors, notably, and without limitation:
[0179] wire shielding and analog ground plan isolation in order to
limit noise interference and parasitic capacitance; or a
combination of a triaxial cable and an optical fiber to guarantee
superior noise immunity.
[0180] There is now described an embodiment of a method implemented
on a computing system, in communication with the sensors, that
performs operations on the signals collected by the sensors to
extract meaning information therefrom.
[0181] According to an embodiment, and referring to the flowchart
of FIG. 24, the data collected by the sensors (step 1100) and
routed with the headphone 10 where noise-reduction components are
provided (step 1200) are then processed by an embedded processor or
sent (preferably wirelessly over a network, or with a wired
connection) to a remote computer system in order to implement
algorithms for data treatment to extract meaningful information
therefrom.
[0182] A combination of signal processing, machine learning, and
artificial intelligence can be implemented to deliver meaningful
results, such as accurate predictions of user concentration from
low-dimensional noisy EEG data.
[0183] Collected EEG signals are first preprocessed. (step 1300)
The preprocessing can include, for example, blind source separation
algorithms, including PCA, ICA, and wavelet decomposition, and
extraction of separable noise sources, including eye blinks and
muscle artifacts. According to an embodiment, thresholding is used
to identify critical noise sources which are non-separable.
[0184] According to an embodiment, the signals are time-filtered
(step 1400) using several low and high-order digital FIR and IIR
filters to remove high frequency artifacts, low frequency and DC
noise sources, powerline noise, and other frequency-based sources
of non-EEG noise.
[0185] According to an embodiment, the EEG signal, after
preprocessing, is separated into features using several signal
processing techniques (step 1500). Time-frequency features such as
FFT, phase delay, cepstral coefficients, and wavelet transforms can
be extracted, for example by applying sliding bins across the
time-series data. According to an embodiment, energetic features
such as hjorth parameters and zero crossing rate are calculated
over windowed bins. Structural information features such as Shannon
entropy and Lyapunov exponents are also calculated. These features
are measured on each EEG channel, or any linear or nonlinear
combination of each channel. The extracted EEG features can be left
unprocessed, or can be post-processed using statistical methods,
such as smoothing, derivatives, or weighted averaging.
[0186] According to an embodiment, in order to describe the state
of the person wearing the headphones 10, the features previously
identified can be fed into a series of machine learning classifiers
(step 1600), which are trained on subsets of the collected data.
These classifiers include but are not limited to LDA, SVM, neural
networks, decision trees, etc. As a result, each classifier
develops the ability to differentiate unique patterns in the EEG
signal.
[0187] According to an embodiment, these classifiers are fed into a
boosted meta-classifier (step 1700), which takes the output of the
individual classifiers as inputs. This meta-classifier can be
trained on an individual's data, to tailor the classifier system to
their unique input and individualize the descriptions or
predictions. According to an embodiment, the output of the
classifier system is fed into a reinforcement learning model, which
determines the likelihood that the user is distracted. The user's
state of concentration and distraction is modeled as a Markov
decision problem, which the algorithm learns to navigate through
use of structures such as Qlearning, and TD difference
learning.
[0188] Feedback can eventually be provided to the user, as
described above in relation with the embodiment of FIG. 1 (step
1800).
[0189] While preferred embodiments have been described above and
illustrated in the accompanying drawings, it will be evident to
those skilled in the art that modifications may be made without
departing from this disclosure. Such modifications are considered
as possible variants comprised in the scope of the disclosure.
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